Location: Bioenergy ResearchTitle: High titer ethanol production from SPORL-pretreated lodgepole pine by simultaneous enzymatic saccharification and combined fermentation Author
Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2012
Publication Date: 10/28/2012
Citation: Lan, T.Q., Gleisner, R., Zhu, J.Y., Dien, B.S., Hector, R.E. 2013. High titer ethanol production from SPORL-pretreated lodgepole pine by simultaneous enzymatic saccharification and combined fermentation. Bioresource Technology. 127:291-297. Interpretive Summary: Soft woods represent a significant source of carbohydrates for production of renewable biofuels, including ethanol. The major barrier to their use is developing methods to extract the carbohydrates efficiently using a scalable process. This paper does much to address this concern. Sulfite pulping has been reinvented so as to prepare biomass for enzymatic extraction of sugars. As the unit operations are already in use by pulping factories, the process is convenient to scale. The prepared biomass samples were successfully hydrolyzed with commercial cellulases and fermented to ethanol in a yeast fermentation to 47.4 g/l final concentration. It is notable that the obtained ethanol concentration is commercially relevant.
Technical Abstract: Lodgepole wood chips were pretreated by SPORL at 25% solids loading and 180ºC for 20 min with sulfuric acid and sodium bisulfite charges of 2.2 and 8 wt/wt % on oven dry wood basis, respectively. The pretreated wood chips were disk milled with the pretreatment spent liquor and water and then separated through pressing. The liquor was neutralized and concentrated through vacuum evaporation in order to conduct simultaneous enzymatic saccharification of the solids and combined fermentation with the concentrated liquor, at up to 20% total solids loading. Fed-batching of the solids was adopted to facilitate their liquefaction and saccharification, as well as to manage instantaneous inhibitor concentration levels. At a cellulase loading of only 9 FPU or 0.06 mL/g untreated wood, a maximum ethanol titer of 47.4 g/L resulting in a calculated yield of 285 L/ton wood.